This invention relates in general to equipment for use with a well having a vertical bore and at least one lateral bore and, more particularly, to a method and apparatus for running into the well two tubing strings which respectively extend to the vertical bore and the lateral bore.
A well for the production of hydrocarbons will have a vertical bore, and often has at least one lateral bore that communicates with the vertical bore through a window. It is possible to simultaneously produce hydrocarbons from both the vertical bore and lateral bore, by running a pair of tubing strings into the well, such that one tubing string is disposed in and effects production from the vertical bore, and the other tubing string is disposed in and effects production from the lateral bore. Although dual tubing string equipment has been developed for this purpose, and has been generally adequate in use, it has not been entirely satisfactory in all respects.
More specifically, each of the two tubing strings can typically have at the outer end thereof a seal assembly, which includes a tube with one or more annular seals therearound. The seals may be damaged as the tubing string is inserted into the well. For example, as the seal assembly is run into the well, it may initially be coupled by shear pins to a locator. The locator is rotationally oriented when it reaches the region of the window, after which the pins are sheared in order to permit the seal assembly to continue moving without the locator. However, the remnants of the shear pins may engage and damage the seals. As another example, the window in the vertical casing may have jagged edges, and the jagged edges may tear the seals if they engage the seal assembly as it is routed from the main bore into the lateral bore.
A further problem is that the tubing string for the vertical bore is normally routed past the window through a passageway having a centerline that is radially offset from the centerline of the vertical bore, but may then need to be moved back toward the centerline of the vertical bore. For efficiency, the diameters of the two tubing strings are usually made as large as possible relative to the inside diameter of the vertical casing. As a result, there has traditionally been no satisfactory way to provide additional structure which would fit within the limited transverse space available around the tubing strings, and which could satisfactorily guide the tubing string gradually back toward the centerline of the vertical bore.
From the foregoing, it may be appreciated that a need has arisen for a method and apparatus for facilitating the use of dual tubing strings in a well, so as to avoid damage to seals of a seal assembly during insertion of the seal assembly, and so as to guide a tubing string past or through a window opening. According to the present invention, a method and apparatus are provided to address this need.
One form of the present invention involves: supporting a protective sleeve for axial movement relative to a seal section between a first position in which an annular seal around the seal member is disposed within the protective sleeve, and a second position in which the annular seal is axially spaced from the protective sleeve; inserting a tubing string into the well with the seal section thereon and the protective sleeve in its first position; and thereafter effecting movement of the protective sleeve from the first position to the second position.
Another form of the present invention involves: an elongate tubing string which can be removably inserted into a well in a lengthwise direction; an auxiliary part supported for upward axial movement along the tubing string away from an initial position; and a releasable coupling arrangement having a coupling state in which the coupling arrangement prevents upward movement of the auxiliary part away from the initial position relative to the tubing string, and having a release state in which the coupling arrangement permits the auxiliary part to move upwardly away from the initial position relative to the tubing string.
Yet another form of the present invention involves: a window assembly having an arrangement for supporting the window assembly within a vertical well bore in the region of a window, the window assembly having first and second tubing passageways therein, and having below the second tubing passageway an upwardly facing deflection surface portion which is inclined to extend downwardly toward the window, the deflection surface portion having a cross-sectional shape which is concave.
Still another form of the present invention involves: a window assembly having an arrangement for supporting the window assembly within a vertical well bore in the region of a window, and having first and second tubing passageways therein, the first tubing passageway having a first portion which has a centerline radially offset from a vertical centerline of the vertical bore, the second tubing passageway having a portion which is axially aligned with the first portion of the first tubing passageway, and the first tubing passageway having an elongate second portion which is below the first portion thereof and which is inclined at a small angle with respect to the centerline of the vertical bore so that an upper end of the second portion is farther from the centerline of the vertical bore than a lower end thereof.